We are studying the organization and regulation of expression of the eukaryotic genetic loci that play a central role in the development of a tissue; the zein gene loci that function during endosperm development in Zea mays. The developing endosperm tissue of maize offers a favorable system since the synthesis of its storage proteins represents the one time expression of genes in which massive amounts of protein are synthesized in a short period of time. The objectives of the proposed research are to: 1. Clone the genome regions of maize that code for zein mRNA. 2. Examine the structural interrelationships among the zein genetic loci and their zein mRNAs. 3. Examine the nucleotide structure of the zein genetic loci by restriction enzyme analysis and nucleotide sequence analysis.